Serbian Novak Djokovic needed just 54 minutes to beat American Andy Roddick, 6-2, 6-1, to advance to the third round of the Olympic tennis event.

Djokovic, bronze medalist in the 2008 Beijing Games, converted all four of his break point opportunities and hit 34 winners to seal a meeting with Lleyton Hewitt of Australia. Hewitt defeated Croatian No. 13 seed Marin Cilic 6-4, 7-5 in one hour and 36 minutes.

"It was the perfect match in every sense. I delivered my best game, I think, so far this year on grass courts," said Djokovic, who Djokovic, who unleashed 14 aces against Roddick.

"I didn't expect to serve as many aces, but both of my matches that I've played here I've served really, really well. So that's something encouraging for the next challenge," added Djokovic, whose victory kept him on pace with Roger Federer in the battle for the No. 1 world ranking.

If both Federer and Djokovic make it as far as the quarter-finals, then Federer must win one more match than Djokovic to retain the World No. 1 ranking. Federer plays Denis Istomin Wednesday.

"He played great. He was just in the zone. The conditions were perfect. He was hitting it well," Roddick said.

"If he is hitting the ball like that, my chance is to serve really well. I didn't serve great today. I hit the ball fine, [but] he was just too good from the baseline. He was seeing it like a basketball today," he added.

In other matches, Andy Murray of Britain advanced to the third round after beating Jarkko Nieminen of Finland, 6-2, 6-4 while Kei Nishikori of Japan beat Nikolay Davydenko of Russia, 4-6, 6-4, 6-1 and Marcos Baghdatis of Cyprus defeated Richard Gasquet of France, 6-4, 6-4, to advance.

In the women's division, Venus Williams barged into the third round after beating Aleksandra Wozniak of Canada, 6-1, 6-3.